110 THE ADDRESSES, LECTURES, ETC., OF 



PRICE'S RETORT FURNACE. 

 To THE EDITOR OP " ENGINEERING." 



SIR, In a paper read by Mr. Bell before the Iron and Steel 

 Institute describing Price's patent retort furnace, and which you 

 publish in your issue of the 8th inst., allusion is made to the 

 Siemens furnace, and I shall be obliged by your allowing me to 

 say a few words in reply. It is stated " The preliminary conver- 

 sion, however, of the coal into a gas is attended with a certain 

 amount of loss, inasmuch as the whole of the fixed carbon is burnt 

 to the condition of carbonic oxide, which means a sacrifice of 

 about 30 per cent, of its heating power." This would be perfectly 

 true if solid carbon were employed without decomposition of 

 water, but as common coal is the fuel burnt, the actual results 

 are different. In the gas producer three operations are performed : 

 in the lower portion the fuel is burnt, and this may be called the 

 zone of combustion ; higher up the carbonic acid takes up a further 

 equivalent of carbon, becoming carbonic oxide, this may be called 

 the zone of carbonisation ; whilst at the uppermost layer of the 

 producer hydrocarbons are produced in what may be called the 

 zone of distillation. The temperature of the first zone would be 

 about 2400 C., and that of the second about 960 C., provided no 

 water was admitted with the air for combustion. The mixture of 

 carbonic oxide and nitrogen resulting from this reaction, and at 

 the temperature of 960 C., has still all the work to do which is 

 accomplished in a gas retort, namely, to deprive the coal of its 

 hydrocarbons and vaporous constituents, amounting to from 30 to 

 35 per cent, of the weight of fuel supplied ; the work done in this 

 third or uppermost zone of the gas producer may be valued at 300 

 heat units per pound of fuel charged,* which would deprive the 

 gases of 270 C. of temperature, reducing that temperature to 

 690. In practice I find that the temperature of the gas-producer 

 chamber does nob exceed 400 C., the difference being due to 

 farther useful work performed by the heat resulting from the first 

 operation, namely, in the decomposition of water introduced below 



* In practice it takes 4 '5 cwts. to distil the gases from a ton of coal. 



